so as the title says... coolant isn't getting sucked back into the cooling system when i let it cool down. So i have to keep on refilling it, but i have no idea why it's not getting sucked back into the cooling system. I'm thinking maybe a clog in one of my lines. What hose sucks the coolant back from the overflow bottle? any help would be appreciated.

 

probably cause its going into the engine. . . are you experiencing white smoke or sweet smelling exhaust?

paul

 

That is NOT a good thing. You are likely a victim of an O-ring problem that is allowing the cooling system to have a positive pressure due to combustion gasses being released into it, and then you no longer have the thermosiphon effect possible when the engine cools down.

Trust me (and everyone else that responds to this thread).....

 

Like the others said - this is symptom of a coolant seal leak.

Run a coolant system pressure test and champagne bubble test to get a better idea, or take it to a good rotary shop. Be prepared for the worst, though.

 

borrow a coolant pressure tester from autozone. you will need either an adapter for the radiator filler boss or a pettit/or similar ast which uses a standard size boss.

pump it up to 14 psi and watch to see if you lose pressure. (you will)

look for coolant seepage to find your leak.

it may be your engine or it could be any of the coolant hoses or fittings.

you only need an AIR LEAK anywhere in the system to completely lose coolant recovery. one pinhole leak will do it.

good luck,

howard coleman

 

hmmmm... did you warm up your engine to over 80deg Celcius? thermostat doesnt open til around that time.. you can fill and fill and it wont go into the engine..



edit: oops bad advice.. i didnt understand the whole first post.

 

http://www.mazdatrix.com/bhose3.htm

Get new hoses & a new ast cap first.

 

yeah, don't immediately jump to the worst case scenerio of a blown engine. Do like the people right above have said. New AST and engine cap. Then ckeck the line from the AST to the overflow bottle for kink or it being pinched by something (IC for example). Also there is a fitting in the middle that connects the line, since it's actually 2 lines that make up the AST / overflow line. Make sure and zip tie them to the plastic fitting if the rubber is getting old.

Tim

 

I've had this problem for about 20K. For some reason it would not pull all the coolant back in all the time. Sometimes I'd check and it would go back to the normal level in the overflow tank. The car never overheated but it did get hotter faster, seemed to be due to some air in the system.

I tried everything. Removed the air multiple times. Replaced the t-stat, tightened up all the hoses, did a pressure check for leaks, etc. Nothing! I knew that I'd be rebuilding the engine so I didn't give it any more thought.

Well I'm tearing apart the motor right now and found something kinda bizzare...

I'll post some pics in a minute.

 

Hey guys, so i hope this isn't a thread hijack but we are experiencing the same prob on my buddies FD...

He was having no problems prior to swapping filter necks (put on a polished one)...Seems to be no leaks anywhere around the neck. He also has the AST elimination kit top on the filter neck.

Something that seemed strange to me with this kit is that there was no pressure spring on the filter neck now...So I really dont see how the system can hold pressure. Because as soon as the temp rises it just has to go a little above the filter neck before it starts dumping into the overflow.

When you eliminate the AST should there be a spring loaded cap on the filternect as there is on the AST?

 

Okay, here's the pics.

When I looked at the underside of the water pump I saw there's a small hole, probably for the bearings to breathe.

Well there's a small lump of crystallized coolant. There's no evidence of a major leak, rather what it looks like is a very small leak that allowed the coolant to sit there and crystallize.

It's possible that the slight leak occurs only during the shaft spinning, and maybe pulls back a small amount of air.

I don't know if this is a common problem, as many others have had similar problems and can't find the source of a leak.

BTW, I've never smelled coolant in the exhaust , nor had white smoke after the car is warmed up, nor problems with hot starts; all possible symptoms of a blown coolant o-ring.


As for:
Yes, the filler cap that goes on the top of the filler neck needs to have the same pressure spring as was on the AST. Otherwise there's no way to hold the pressure in the system.

 

Did you not read the post? I said there was no indication of any coolant spilling anywhere, none when I pressure tested it, no coolant running down the front of the engine, no "pissing coolant".

 

Mine was doing that last summer. I put new caps on and the fluid level in the overflow is now dead on.

 

dude... the filler cap does not have a spring on it.. it's supposed to be a straight seal. The only cap with a spring on it is the AST cap.

 

Yes, that is why we are talking about the AST elimination.

 

WTF?!? Don't people know how to read anymore?

That means he no longer has a pressure cap, nor an AST! Therefore he needs to have some kind of pressure cap, right?

 

whoo.... i really hope it's just the hose from the AST to the overflow, because that's the original hose and it is crumbling just a little with 78000+ miles on it... that was the only hose that I didn't replace when I bought a new set like 2 months ago. I think i'll check that one out... as for sweet smelling exhaust.. nope... but i do get a different smell when i first start the car up. I get a super rich smelling gas smell coming out for about 30 seconds, and than it blows a moderate amount of white smoke for about a minute and a half. then i get no more smoke.

 

That exhaust is normal .

 

i dont get it?? your water pump is bad and leaking? did you think the green build up is from the coolant gnomes who steal coolant and socks at night?

 

I have a similar problem that happened recently, so pointers would be appreciated.

The water level used to sit at the top of the filler neck. Now, it sits about 2-3 inches below the top. The only thing that changed between then and now is the coolant itself... I flushed it and it stopped filling all the way up. The AST is completely full. I replaced all 14 coolant hoses about 6 months ago, including the one to the overflow tank. I thought it might have been my caps (which I replaced 12 months ago), but replacing them yielded no difference. There are zero leaks. The level of the overflow tank does not decrease, nor does the level in the filler neck when checked cold decrease. The tube to the overflow tank isn't clogged - I checked that. My car passes the champagne bubble test, too - there's no bubbles at all, nor is there any sweet-smelling exhaust. I'm kind of at wits end here... I can't figure this out! Any other odd suggestions?

Thanks!

Take care,
Shad

 

Shad, do you have to fill it up? If you don't put any coolant in it, doe sit stay 2 to 3 inches below the top? Does it go any lower? If it doesn't don't worry about it, not worth getting grey hair over it.

Tim

 

I guess not.

The point was that the pump was working correctly, and the leak was not visible AT ALL. The hole is on the underside of the pump, therefore not visible unless you take it off. Since I saw NO leaks anywhere, NO coolant on the front of the engine, NO coolant on the waterpump, HOW was I supposed to figure out that there was coolant crystallized underneath?

The level of coolant remained relatively normal, just at times the coolant wouldn't get pulled back into the system, meaning there was more than likely a leak somewhere. I could NOT find the leak.

I posted this because I thought it may help for some people to look another place where they might not have thought to look.

Should I have explained this in gnome terms so you could get it?

 

Hello-

No, I don't have to fill it up... it just sits a little low. About the gray hair though... it's too late. I started when I was 14, so ten years later... :-)

Thanks for the info. Curiosity question, though: why would it suddenly go from never happening to happening all of the time? It just seems weird...

Thanks,
Shad

 

Hi Howard...is the 14psi pressure test the norm? We were looking for a cap for the filterneck and we couldn't remember the pressure so first we got a 13psi cap....Then the God book said something like 16-20 psi...So would you just want to pressure test a couple of psi lower than the max psi cap it would take? What psi cap are all you guys running? I am almost sure I have a 13psi cap on my AST and haven't had any ill effects.

 

I think there's a little confusion on the radiator caps...

There are 2 types of radiator caps - a radiator cap and a fill cap. The fill cap is just simply the top section of a radiator cap with the rubber seal - that's it. The radiator cap has the spring and another disc coming from it with another rubber seal.

The fill neck that has the nipple going to the overflow tank HAS to have a radiator cap. The fill cap can ONLY be used on a car with an AST on the neck on top of the thermostat housing with NO overflow tank nipple on the neck.

The fill cap is just simply an easy-to-remove access point to put coolant in the system. You *can* put a regular radiator cap in there, but it's basically functioning as a fill cap. The pressure rating, design, etc. of the cap has NO bearing if it's being used as a fill cap.

As with thermostats, I recommend using a Mazda radiator cap. Parts store caps don't seem to fit as well, and are a bit loose. Mazda is the only source for the fill caps as far as I know - that's not a common aftermarket thing.

Dale